Submitted to: Observation and Estimation of Carbon Cycle in Terrestrial Ecosystems
Publication Type: Abstract Only
Publication Acceptance Date: 9/30/2002
Publication Date: 10/10/2002
Citation: Daughtry, C.S., McMurtrey, J.E., Hunt, E.R., Gish, T.J. 2002. Remote Sensing Crop Residu Cover and Conservation Tillage Practices [abstract]. Observation and Estimation of Carbon Cycle in Terrestrial Ecosystems [CDROM]. Interpretive Summary:
Technical Abstract: Quantifying crop residue cover on the soil surface is important for evaluating the effectiveness of conservation tillage practices. Current methods of measuring residue cover are inadequate in characterizing the spatial variability of residue cover over large fields. The objectives of this research were to determine the spectral reflectance of crop residues and soils as a function of water content and to evaluate the limits of discrimination that can be expected. Spectral reflectances of corn and wheat residues plus five diverse soils were measured over the 400-2400 nm wavelength region at a wide range of moisture conditions in the laboratory. Reflectance factors for scenes varying proportions of crop residues and soils were simulated. Additional spectral reflectances of scenes with mixtures of crop residues and soil were acquired in fields near Beltsville, MD. The spectra of dry crop residues displayed a broad absorption feature near 2100 nm, associated with lignin-cellulose, that was absent in spectra of soils. The relative depth of the lignin-cellulose absorption feature, defined as Cellulose Absorption Index (CAI), was positive for all crop residues. In contrast, all soils had negative CAI values. The wide range of CAI values expected for dry and moist conditions makes quantification of crop residue cover feasible. Analysis of airborne hyperspectral images demonstrated that this reflectance technique can provide field- and regional-scale maps of crop residue cover and conservation tillage practices.